ARTICLE IN BRIEF
Investigators reported that the risk for a major stroke was double in patients who had an aortic-valve prosthetic delivered through a catheter (5.1 percent after one year) compared to 2.4 percent for those who had surgery.
Patients with aortic-valve stenosis have been having surgery to replace faulty valves for more than 30 years. In 2002, cardiologists developed a less invasive transcatheter technique that was initially tested in patients who were not candidates for surgery. The technique reduced mortality in patients who had no other therapeutic options.
Researchers have since designed a study to compare surgery and two different routes of transcatheter aortic-valve implantation in high-risk patients who were able to withstand a surgical procedure. The question at hand: Was surgery superior to the less invasive technique?
The answer, according to a study published in the June 9 New England Journal of Medicine, is no. But while mortality at one year was 24.2 percent in the transcatheter patients versus 26.8 in the surgical patients, the researchers reported that the risk for a major stroke was double in those who had an aortic-valve prosthetic delivered through a catheter (5.1 percent after one year) compared to 2.4 percent for the surgical group (p=0.07). There were also more major vascular complications, 11.3 percent versus 3.5 for those undergoing surgery (p<0.001).
Craig R. Smith, MD, chairman of surgery at Columbia University Medical Center-New York Presbyterian Hospital in New York, said hospital stays were shorter in those who had the less invasive procedure. But the neurological complications raise concerns and will probably inflame the debate about the use of the technique in patients who are not considered high risk. That includes younger patients who may be asymptomatic or have mild symptoms. Also, it is not clear how long the prosthetic valves will work.
Dr. Smith said that most strokes were procedure-related and embolic so that it's possible that the risks will diminish as the catheters get smaller and the surgeons gain more skill.
He explained that in transcatheter aortic-valve replacement, the surgeon delivers a bioprosthetic valve on a catheter through the femoral artery or through the left ventricular apex. Once the catheter is inside the artery, a balloon is inflated that literally crushes the calcium out of the way.
Dr. Smith admits that the neurological complications might be a barrier in the low-risk patient. The study team is about to begin a study to test the device in this patient population.
“In the absence of long-term follow-up data, recommendations to individual patients must balance the appeal of avoiding the known risks of open-heart surgery against the less invasive transcatheter approach,” he and co-investigators wrote.
Aortic stenosis is life-threatening if left untreated. In the first leg of the trial, published last October in the New England Journal of Medicine, the researchers reported that there was a 20 percent increased survival in those patients who had transcatheter-placement compared to those in a historical control population of patients who were not candidates for surgery.
EXPERTS WEIGH IN
In an editorial accompanying the study, Hartzell V. Schaff, MD, a cardiovascular surgeon at the Mayo Clinic in Rochester, MN, asked how a procedure in which the risk of neurologic complications is twice that of surgical replacement has become adopted so widely and rapidly? (The device is growing in use in Europe, where it is approved for use.)
“The continued surveillance of patients in this study will be critically important to determine the durability of the transcatheter prosthesis and to assess the risk of late thromboembolic events,” said Dr. Schaff. He speculated that the insertion of the prosthesis without removal of the diseased aortic valve “creates an irregular zone around the stent that may predispose to thrombus formation.”
Larry B. Goldstein, MD, professor of medicine (neurology) and director of the Stroke Center at Duke University, said that neurologists are generally not involved in the decision-making process when it comes to aortic-valve replacement. Recommendations on which procedure to use would generally come from the cardiac surgeons or cardiac interventionists.
Still, he said, “neurologists should be aware of the potentially higher stroke risk with the transcatheter procedure and work with cardiology teams to better assess patients for cognitive symptoms after the procedure and following stroke.”
A federal advisory panel is now being established to review the study information on the transcatheter device for aortic-valve replacement.
THE TRIAL: PROTOCOLS & STATISTICS
- 699 high-risk aortic stenosis patients across 25 hospitals throughout the US were randomly assigned to undergo either transcatheter aortic-valve replacement (transfemoral or transapical) or surgical replacement.
- The primary endpoint of the study was death by any cause at one year.
- 351 patients were assigned to surgery, 248 to transfemoral- placement and 103 transapical-placement.
- Forty-two of the 699 (four in the transcatheter group and 38 in the surgical group) did not undergo the assigned procedure.
- As part of the study design, the patients assigned to receive the transcatheter aortic-valve replacement received heparin during the procedure and dual anti-platelet therapy (aspirin and clopidogrel) for six months.
- Four patients died during the procedure, three during the transcatheter-placement, and one in the surgical group.
- The transcatheter procedure was stopped or the plans changed in favor of surgery in 16 patients. One of the surgical patients was switched to a transcatheter-procedure when it was found that the aorta was extremely calcified.
Smith CR, Leon MB, Pocock SJ, et al, for the PARTNER Trial Investigators. Transcatheter versus -surgical aortic-valve replacement in high-risk patients. N Engl J Med
2011;364(23):2187-2198. E-pub 2011 Jun 5.
Schaff HV. Transcatheter aortic-valve implantation—at what price? N Engl J Med